Even though Wikipedia classifies it as vaporware, there are prototype cards and manuals floating around showing that these cards were in fact designed and contained programmable pixel shaders, notably:
- The Pyramid3D GPU datasheet: http://vgamuseum.info/images/doc/unreleased/pyramid3d/tr2520...
- The pitch deck: http://vgamuseum.info/images/doc/unreleased/pyramid3d/tritec...
- The hardware reference manual: http://vgamuseum.info/images/doc/unreleased/pyramid3d/vs203_... (shows even more internals!)
(As far the companies go: VLSI Solution Oy / TriTech / Bitboys Oy were all related here.)
They unfortunately busted before they could release anything, due to a wrong bet in memory type choice (RDRAM, I think) and letting their architecture rely on that, then running out of money, perhaps some other problems. In the end their assets were bought by ATI.
As for 3dfx, I would highly recommend watching the 3dfx Oral History Panel video from the Computer History Museum with 4 key people involved in 3dfx at the time [2]. Its quite fun as it shows how 3dfx got ahead of the curve by using very clever engineering hacks and tricks to get more out of the silicon and data buses.
It also suggests that their strategy was explicitly about squeezing as much performance out of the hardware, and making sacrifices (quality, programmability) there, which made sense at the time. I do think they would've been pretty late to switch to the whole programmable pipeline show, for to that reason alone. But who knows!